26 Sep
2005
26 Sep
'05
6:48 p.m.
> You've obviously never run into a NEC 9800 PC
(or just about any other
On Mon, 26 Sep 2005, Tony Duell wrote:
Indeed I haven't.
Maybe the engineers just REALLY preferred 8" drives?
version of Japanese MS-DOS) diskette. 77
cylinders of 5x1024 sectors,
spinning at 360 RPM, just like an 8" drive.
I am puzzled as to why that would spin at 360rpm. The format would be
possible on a '720K' drive turning at 300 rpm using the normal 250kbps
double-density data rate. If you double the data rate to 500kbps, you
should be able to get more that 5 sectors, even at the faster spindle
speed.
What was the data rate at the interface connector of these Japanese machines?
NEC is probably NOT using a WD FDC :-)
The index gap has to be larger for the basic 765 setup than with WD.
The rest of the gaps are similar between NEC and WD.
At 300K bits per second with 360 RPM, the format would be similar to
250K bits per second at 300 RPM, which is what we are used to.
5 * 1024 is a good format for that.
Getting 5 * 1024 with 250K bits per second at 360RPM would require some
very tight sector gaps.
500K bits per second at 360 RPM can handle 8 * 1024, or 9 * 1024 with
tight gaps.
Not having got anything that supports the useless
serial botch interface,
I've not looked at such drives.
I've seen an LED map light that plugs into and gets its power
from USB. It seemed to work OK.